What is fastest, @Entity or @Embedded?

Im new (today) to the NoSql MongoDb and trying to understand the Morphia.

I want to have one @Entity like this:

If i have 3 Tables (Collections) named

Stat

Friendlist

Userdata

I save UserData.Class in Userdata right and Statistic.Class in Stat and so on...

My thought was if i give each user a unique ObjectId UUID nr and then every Statistic and FriendList having this UUID nr as there ObjectId. Because if the program need to run statistic only, it will load/work against Statistic only.

@Entity
public class UserData {

    @Id private ObjectId id = "UUID 123456789;
    public String userName = "";
    public String password = "";    
    @Embedded
    private Statistic statistic;
    @Embedded
    private FriendList friendList;
}

If there are like 18000/hour request to get the UserData would it not be faster to declare them like this:

( i use the same ObjectId and they ares stored in separate Collections (tables)

@Entity
public class UserData {

    @Id private ObjectId id = "UUID 123456789;
    public String userName = "";
    public String password = "";
}

@开发者_运维知识库Entity
public class Statistic {

    @Id private ObjectId id = "UUID 123456789;
    public int loginTimes;
    public String gps;

}

@Entity
public class FriendList {

    @Id private ObjectId id = "UUID 123456789;
    public ArrayList<String> fiends;
}

I think that the correct is use DBRef or Embedded.

If you want some object of the list in other object too, use DBRef, if not, use embedded.

For example, in a blog post, the comments will never be used in another post, so, its embedded.

So, use somehting like:

@Entity
public class UserData {

@Id private ObjectId id = "UUID 123456789;
public String userName = "";
public String password = "";    
@Embedded
private Statistic statistic;
@Embedded
private List<Friends> friendList;
}

hope it helps.

Embedded is always faster because Reference stored in different physical location.